Executive Producer: Gene Roddenberry
Producers: Gene L. Coon + John Meredyth Lucas
Associate Producer: Robert H. Justman
Script Consultant: D. C. Fontana

Writer: Robert Bloch
Dir.: Joseph Pevney

Captain Kirk: William Shatner
Science Officer, First Officer, Cmdr. Spock: Leonard Nimoy
Dr. Leonard "Bones" Mc Coy: DeForest Kelly
Lt. Sulu: George Takei
Lieutenant Commander Montgomery Scott: James Doohan
Lieutenant Uhura: Nichelle Nichols

Korob: Theo Marcuse
Sylvia: Antoinette Bower
Jackson: Jimmy Jones
Lt. DeSalle: Michael Barrier

Stardate 3018.2

Pyris VII. Kirk, Spock, McCoy, Sulu and Scott beamed down on the planet. They encounter several facets of human superstition in shape of witches, a warlock and others all surrounded by fog and distant cries and noises. Sulu and Scotty act strange – functioning to orders without any sign of any own will. Behind the scenes are Sylvia and Korob, two aliens who use supernatural powers to conquer planets but need to assume human forms with the help of a matter transmuter to survive on the planet. 

They try to gain the Enterprise people's support by offering them every kind of precious things and then by treatening the Enterprise safety. When that does not work, they put Kirk and Spock in chains, while McCoy is about to undergo the same brainwashing Scotty and Sulu experienced. After Kirk referred to him as "Bones" and at the same time looks at a skeleton in chains beside him, he goes on referring to him as "McCoy" or "Doc" only. Sylvia loves her new body and tries to win Kirk's affection. 

Korob becomes aware of this and helps them to escape. They are followed by a big cat (Sylvia). Out of the place and on the surface of the planet Kirk and friends are trapped by them. In a sudden move Kirk destroys their transmuter device which they had handled like a magic wand. The destruction makes all fantasy products vanish, bring back Sulu and Scotty to normal and leave only two tiny creatures (Spock: "... not a desirable life form ..."): Sylvia and Korob in their natural appearance which cannot stand the planet's atmosphere. They die.